The human intestine is a remarkable organ which stores 90% of the body?s important neurotransmitter, serotonin, in enteroendocrine cells (EECs). Serotonin and other EECs-secreted hormones play critical roles in regulating human feeding behavior and satiety, and their dysregulation leads to overeating and a host of other diseases. For these reasons, there is a need in the therapeutics marketplace for in vitro intestinal EECs platform that precisely recapitulates the physiology of in vivo intestines. To meet this need, Altis Biosystems Inc., an early stage biotechnology company, will collaborate with scientists at the University of North Carolina at Chapel Hill to develop a novel, primary-stem-cells-based, in vitro intestinal model (termed RepliGut) that contains sufficient EECs for studying serotonin secretion. The platform will be designed with the eventual goal during Phase II of creating systems for assaying a variety of intestinal hormones in a high-content screening. The goal is to validate the RepliGut product and bring this technology to therapeutics market. The collaboration represents an ideal opportunity for the translation of an academic technology to the marketplace through the NIH sponsored SBIR program. In this Phase I SBIR, this collaboration will optimize the RepliGut 96- well platform for EECs cell lineage allocation, investigate cell variation, quantify serotonin secretion, and validate the platform with a small-scale compound screen for serotonin.